The present invention relates to the winning of mineral values from underground ore bodies. More particularly, the present invention relates to an improved method and system for effecting in-situ mining of ore bodies containing mineral values which lie in generally horizontally extended attitudes and are overlain by surface features or an overburden which would handicap usage of conventional mining techniques.
Various methods are known for winning minerals from underground ore bodies; typical are vertical shaft access mining which involves mechanically extracting broken ore from the deposit by driving entries and/or stopes into and throughout the ore body, and chemical recovery by a variety of underground in-situ solution mining or chemical-reaction processes; examples of these methods are disclosed in U.S. Pat. Nos. 2,251,916, 2,682,396, 2,976,690, 3,022,986, 3,695,711, 3,822,916, and 3,873,156.
While such processes have utility in most circumstances, they are not efficient in situations where a generally horizontally extending ore body is covered by an overburden which is of such nature as to handicap conventional vertical shaft or surface operated solution mining approaches to the ore body. The ore body may, for example, be overlain by a body of water, or by an overlying geological formation which is difficult, and therefore expensive, to penetrate.
Still another situation in which conventional method access to an ore body is uneconomical or otherwise impracticable occurs wherever the sought-for mineral is located under a densely populated or industrialized area. In these cases employment of typical vertical shaft access mining systems could require purchases of expensive above-ground real estate or could conflict with zoning restrictions and environmental requirements.
The above mentioned disadvantages of the prior art are particularly troublesome and may preclude economical exploitation of relatively thin layered mineral deposits such as are located at substantial depths below the earth's surface. There thus exists the need to provide a mining technique whereby a horizontally extended ore body with the aforementioned impediments may be more efficiently and inexpensively mined.